David Clark Connector PJ-051

[Mikebits]

Can anyone tell if this is a David Clark only part or does it have a equivalent? Looking for a cheaper source.
**broken link removed**

It is used in a fire engine intercom system.

 

[MikeMl]

It is a standard 3/16 (0.206)" Tip, Ring, Sleeve Aircraft Mic Plug. What makes that particular one expensive is the gold plating and the David Clark name... Here is a cheaper alternative. I have used dozens of them.

 

[Mikebits]

Perfecto The reason I asked is that we need to replace some David Clark headsets. https://www.mypilotstore.com/mypilotstore/sep/5551
but at $350.0 a unit I want to just use a cheaper headset unit and then change the connector. Something like this unit.
https://www.mypilotstore.com/MyPilotStore/sep/6371

Thanks

 

[MikeMl]

All aircraft headsets have a 0.206" mic plug. The headphone plug is 0.250". Why would you need to change the mic plug?

 

[killivolt]

I just sent the Dave Clark, Company URL to my buddy.

His name, Dave Clark. But, how generic is that....... Dave .........Clark

There's probably thousands. He's an Aerospace Machinist.

Who new?

 

[Mikebits]

All aircraft headsets have a 0.206" mic plug. The headphone plug is 0.250". Why would you need to change the mic plug?

Well, the Clark headset schematic is below. The drawing only shows one connector for both headphone and mic. The other head sets have two connectors. Also I did not know all headsets use the same .206" plug. Do they all handle 4 conductor like the one I linked?

Thanks

 

[MikeMl]

Well, the Clark headset schematic is below. The drawing only shows one connector for both headphone and mic. The other head sets have two connectors. Also I did not know all headsets use the same .206" plug. Do they all handle 4 conductor like the one I linked?

I didn't know that fire engines only have one plug...

The connector you linked off EDMO only has three connections, tip, ring and sleeve. That second ring is not hooked up. There are only three terminals under the screw-on barrel. How are you going to add the switch?

 

[Mikebits]

I didn't know that fire engines only have one plug...

The connector you linked off EDMO only has three connections, tip, ring and sleeve. That second ring is not hooked up. There are only three terminals under the screw-on barrel. How are you going to add the switch?

All I know is this. We just picked up a new pumper (used but new for us). My Cap sends me a email with a part number a Clark model U3800 and he tells me to look for some headsets for this intercom system. Oh, and I need to find low price. I was hoping to find one with switch built in.

I just looked up the headset mentioned above that is matched for U3800, and went from there.

 

[Mikebits]

Hope I did not sound snarky before, did not mean to. Anyways, we need intercoms in the engine because it is very noisy in the cab. The crew cab is separated from the drivers compartment, and also, the diesel engine is also in the crew cab, only covered by metal plates, so real hard to hear anybody.

I got a chance today to look at the setup a little and took a few photos. Basically there is the master unit U3800 and some other small boxes distributed in the cab, one box allows PTT with the radio, the other boxes just do intercoms within the engine. I am attaching some pics. I only could find a number on one of the small boxes, U3811.

So what I am looking for is a way to get headsets cheaper than the new David Clark ones. But not sure best way to go about it.
U3811 https://www.electro-tech-online.com/custompdfs/2013/02/PL19512P-58.pdf
U3800 Master unit https://www.davidclark.com/intercomsys/3800mod.htm

 

[MikeMl]

On the "official" DC headsets made to be used with the "firetruck intercom", is there a "PTT" switch built-in to the headphones, or is it on the box that the headphone plugs into? The reason I ask is because if you buy "aircraft" headsets, there will not be a switch in the headsets. You also need to check the type of microphone circuit in both headsets.

A description of how aircraft mics work is here. Make sure the ones for the firetruck work the same way.

I have an older aircraft headset I could send you so that you can hack one before spending any $.

 

[Mikebits]

Here's the thing, we picked up our pumpers used. They came with the David Clark intercom system (U3800) but no headsets were included. From what I have seen in other setups, all crew members in the cab can hear the audio from the radio, but not all can talk over the air, usually only the driver/operator and captain seat can. All members however can communicate via headset to one another with a mute function on the headset. In our cab their is a Box labeled Spectra with a PTT switch which I assume is for over the air. If I been reading the David Clark website correctly, we need H3000 series headsets or equivalent. David Clark is just so darn expensive, not as bad as Bose but still pricey. I am hoping to save at least half that, though might not be possible.
Thanks Mike

 

[MikeMl]

There are likely two different PTT circuits, one that puts the headset mic audio onto the local intercom bus (or is that one on a VOX?), and the other other is for the driver or copilot only to connect their respective mic to the FM radio.

In aircraft, the local intercom has multiple mics active, any one of which can open the intercom VOX so that crew mates will hear what is being said. The VOX circuit is there so that cockpit noise is muted when no one is talking. If the pilot or copilot wants to transmit on the radio, they mash a PTT switch on the yoke (stick), which isolates just that one mic away from the intercom, and redirects it to a radio. The crew can keep blabbering even while the pilot is talking on the radio.

My question remains. Does a back-seater have to push a switch to be heard on the local intercom, or is there a VOX?

 

[Mikebits]

From my experience on engines, we can talk and speak locally unless we depress the mute button which blocks our voice transmission. The mute button is on the headset. This is intercom only and not over the air.

 

[MikeMl]

From my experience on engines, we can talk and speak locally unless we depress the mute button which blocks our voice transmission. The mute button is on the headset. This is intercom only and not over the air.

Okay, the aircraft headset does not have a "mute" button. No reason you couldn't add one. I am guessing all it would have to do is break the wire between the mic element and the plug. If you didn't add a mute switch, all headsets would have a hot mic all the time...

 

[Mikebits]

It seems the fire/rescue headsets are a real niche market and David Clark is one of the few makers, hence the high prices. I think we may have to bite the bullet.